Electronic devices often consist of several individually packaged integrated circuits (IC) for different functions, e.g., logic circuits for information processing, memory for storing information, and I/O circuits for information exchange with the outside world. A System-in-Package or SIP is a device that incorporates multiple chips, which make up a complete electronic system, into a single package. In the stacked chip assembly of System-in-Package, all of the individual chips are assembled in a single package, which allows space savings. Furthermore, SIP technology reduces the development costs for electronic application devices in comparison with System-on-chip technologies because different functionalities of the device can be assembled and updated in a modular manner. In three-dimensional die stacking, through-substrate vias are used for connecting different circuits on different chips.
In most electronic application devices, including for instance radio frequency devices and devices requiring DC-DC conversion, passive components like resistors, capacitors and inductors are an essential factor determining the size and cost of respective application devices. The large number of required passive components is a major factor in the assembly line production and yield. Therefore, an integration of passive components into a wafer has increasingly been considered as an alternative to basic surface mount device (SMD) components. In particular, the integration of high-density capacitors into a substrate has the advantage of allowing a miniaturization.
US 2002/0030216 A1 discloses a capacitor integrated into an interconnect stack of a chip. From F. Roozeboom et al., Int. J. Microcircuits and Electronic Packaging, 24(3)(2001), pp. 182-196, trench capacitors are known, which are integrated into a silicon substrate. A capacitance density between 20 and 100 nanofarad/square millimeter (nF/mm2) can be achieved with this technology.
However, the integration of such trench capacitors with high capacitance densities into a passive integration device for a system in package requires a rather complicated processing and is therefore not cost-effective.